Facebook is symmetric.
Each time you add someone as a friend, they have to approve the connection and add you as a friend as well. A two-way relationship is required to have any relationship at all. Typically people share personal information (photos, contact details, etc.) on Facebook that, though it may not be highly sensitive, is probably more than you’d want to share with people you don’t know. So Facebook friendships are generally reserved for those you have at least some connection with.
Twitter, on the other hand, is asymmetric.
You can follow someone without them needing to follow you back. It’s a one-way relationship that may or may not become mutual. This enables you to follow people who may add interesting or insightful commentary that you can learn from (or laugh at), even though you don’t know them personally. Eventually, through interaction and dialogue, they may choose to return the follow; but even if they don’t, they can remain a voice of influence or levity in your life.
What’s this have to do with anything?
Some Twitter Newbies don’t recognize this basic (but huge) difference between the two social media platforms. They’re bothered when “someone they don’t know” follows them, and they wouldn’t dare choose to follow someone they have no connection with. And in doing so, they miss out on the power of asymmetry and the opportunities to connect with people they wouldn’t normally interact with.
Twitter is about engaging. Conversation. Interaction. And the chance to hear the voices of those you normally wouldn’t.
When you see friends tweeting quotes or links from others they admire or enjoy, link over and check out their Twitter profile. Scan through their timeline. If you like what they have to say, go ahead and follow them. Even though you don’t know them.
I dare you.